A conventional operation mechanism 7 for locking or unlocking the front suspension system for bicycles is shown in FIG. 8, and generally includes a base 71 with two lugs 72 and a hole 73 to which the handlebar of the bicycle (not shown) is securely connected. A first lever 74 is pivotably connected to the base 71 by a shaft 743 extending through the lugs 72 of the base 71, and includes a passage 741 and a first pin 742. An end of the operation cable is engaged with the passage 741 and the first pin 742 extends through the lever 74. A second lever 75 includes a torsion spring 751 and a positioning portion 752, wherein the second lever 75 is pivotably connected to the base 71 by extending a second pin 753 through the lugs 72. The pin 742 is cooperated with the engaging portion 752. When the first lever 74 is pivoted, the second lever 75 is moved to a locked position top lock the front suspension system. When the second lever 75 is pivoted, the first lever 74 returns to its initial position to unlock the front suspension system.
However, the first and second levers 74, 75 are respectively located at two different positions of different heights, and the operation directions of the first and second levers 74, 75 are opposite to each other, so that the operation is not convenient to the users. Besides, the coefficient of elasticity of the torsion spring is so large that the users have to press the first lever and the second lever by a significant force and angle, and this is not suitable for the users who have less muscle force. Furthermore, the user's finger could be clamped by in gap between the first lever and the handlebar.
The present invention intends to provide an operation mechanism for locking or unlocking the front suspension system for bicycles, and the operation mechanism improves the shortcomings of the conventional operation mechanism.